For example, the atherothrombosis such as the myocardial infarction causes serious thrombus formation such that an atheromatous plaque is broken at an arteriosclerosis site, platelets are adhered on collagen including tissue factor exposed to the bloodstream. Further, the platelet aggregation, the activation of a blood coagulation system, and the like complexly occur resulting in serious obstructive thrombus. Heart disease such as myocardial infarction, is a serious disease and is the second leading cause of overall deaths in Japan.
However, thrombus formation proceeds only in an atherosclerotic region in the myocardial infarction, and a thrombotic tendency in the whole body is not extremely proceeded. In-vitro examinations are unsuitable for evaluating the thrombotic tendency in such a thrombosis and the monitoring of the antithrombotic effect in the antithrombotic therapy. Thus, it is important to make comprehensive evaluations on coagulation and platelets (adhesion and agglutination) in the presence of the bloodstream.
Heretofore, the blood coagulability has been evaluated by determining activated partial thromboplastin time (APTT), thromboplastin time (PT) using the plasma. The APTT mainly reflects intrinsic coagulation and the PT mainly reflects extrinsic coagulation. The examination of blood platelets is carried out by using platelet-rich plasma and adding a platelet-activating substance such as ADP or collagen to thereby evaluate the aggregating property of platelets from a change in transmittance thereof or the like. In addition, the coagulation time of the whole blood can be determined with the whole blood clotting time, the whole blood clotting time after calcium re-addition, and the like.
Further, an examination system using the whole blood employs thromboelastogrm, which monitors the activations of clotting factors, the platelet agglutination, and the like.
However, thrombus grows under a blood flow in vivo. In contrast, the above examination method or the like is determined in-vitro that is in the closed state. Thus, the status of in-vivo thrombus growth cannot be observed.
As proposals for solving the above problems, Patent Document 1 and Non-patent Documents 2 and 3 disclose the method including bringing the blood provided with an antithrombotic drug to be evaluated to pass on a collagen cell and monitoring the adhesion or agglutination of the platelets by fluorescently-labeling the platelets with a confocal microscope.
However, in the invention described in the document the observation is carried out under the presence of an anticoagulation drug. Thus, the fact that a thrombus which is caused by the adhesion or agglutination of platelets induced by the blood coagulation system is not formed or decreased property to form thrombus is evaluated by monitoring a morphological change in platelet. Thus, the evaluation does not reflect the platelet activation interlocking with coagulation system. Therefore, such an invention is favorable for the evaluation of the efficacy of an antiplatelet drug but is unable to monitor a thrombus itself and the whole process of thrombus formation. In addition, a fluorescence microscope is expensive, so it can be hardly used for general examination.
Further, in Patent Document 2, the fluidity of the anticoagulated blood is determined by passing the blood through a fine-comb-like silicon cell. Likewise, the process of Patent Document 2 also uses the anticoagulated blood, so the influence of a coagulation system cannot be determined. In addition, the viscosity of blood in the process has large individual variations and in diurnal variations, so it is difficult to reflect drug therapy using the system.
The platelet is activated by the coagulation system, and the coagulation system is promoted by activated platelets. Therefore, the efficacy of an antithrombotic drug cannot be observed in the anticoagulated blood, because activation of platelet is also suppressed by the anticoagulation treatment. In addition, non-anticoagulated blood can not used in an examination, because it promptly forms clot.    Patent Document 1: JP 2004-251630 A    Patent Document 2: JP 2006-145345 A    Non-patent Document 1: Blood. 1990; 75:390-398    Non-patent Document 2: Blood. 1999; Aug. 1:94(3):968-75